Di-cyclohexyl amine salt of acid phosphate di-esters



' "esters and diacyclohexy'l amine are chemically Patented July 9, 1946UNITED ATE PATENT- orncs DI-CYGLOHEXYL AMINE SALT 'OF ACID PHOSPHATEDIE-,ESTERS Herschel G. "Smith, Wallingford, and Troy "L. Cantrell,"Lansdowne, Pa., assignors to Gulf Oil Corporation, PittsburPennsylvania gh, Pa, a corporation or No Drawing. Application ,March 19,1945',

.Serial No. 583,653

'- '12 Claims. ((1260-4611) This invention relates to di-cyclohexylamine 'salts or ac'id phosphatev di-esters, and it comprises il-solu'bsubstantially neutral addition prodju'cts'offdi cyclohexyl amine andacid phosphate iii-esters of alkylated phenols, said neutral addi 3mm"productsfleeing useful as rust preventive {compounds-or rustinhibitors;and it further comfpri'ses metho'dsof making said neutral addition"products wherein "the said. acid phosphate dileum'lubricants'andmineraloil compositions containing'minoramounts of the substantially neutraladditionproducts of di-cyclohexyl amine and acid phosphate (ii-esters ofalkylated phenols as rust inhibitors or rust preventive compounds. Thepresent application is directed to suchrust "inhibitors'or rustpreventive compounds, per se. "'That is, the present invention relatestonew oil-soluble, substantially neutral addition salts of di-cyclohexylamine and acid phosphate (ii-esters of lalkylated phenols. Generically,these neutral addition salts may be represented by the followwherein Rrepresentscyclohexyl group and R, ,R and 'R" represent hydrogen or analkyl group, at least one branched chain alkyl group being present.

As a class, the above amine salts are relatively 'non' -volatile, evenat elevated temperatures. Most of them are oily, viscous liquids at roomtemperatures. Others are soft, waxy solids which melt to oily liquids atslightly elevated temperatures. All "of them are insoluble in water andaqueous liquids and are resistant to hydrolysis. Indeed,

"these oily and waxy amine salts are quite water-' repellent. A1s'o,they are relatively stable comf'ponnds.

For instance, they can be heated to elevatedtemperatures as stated ante,and this is 'petrolatum and mineral oils. However, if heated toexcessive temperatures, say 280" "Fuor above,

"'for' long' periods, they become converted into correspo'riding amidecom-pounds, Water i-split oil at such "higher temperatures;

being Generically, our new amine salts are readily soluble inoi1S,-'bOt-h mineral oils and fatty .ons.

*"Ofcoursej-their solubility varies -some\vhat with a particulate andamine salt, but is quite hi'gh in general; Further, in addition tobeing-readily tsdl-uble in m'ineral oils,'they are readily miscible with"other hydrocarbons, such as ipetrolatums, waxes and volatilehydrocarbon liquids, and coating"compositions containing the same Ltheyfleeing readily soluble in hydrocarbon liquids-particularlyvolatileihydrocarbon solvents. When incorporated inhydrocarbons, such asm'ineral oils and the like, they impart marked anti-rust qualitiestheretm as shown in our prior application serial li o.60 15056; In other"words, as described "and illustrated in thatapplication, our :newdicyclohexylamine salts rare excellent :rust preventive compounds :orrust inhibitors.

1 Thedi-cyclohexyl .amine, employedias one reactant, is a well knownI'chemical compoundrcom- -merciallysavailable as'a substantially'purexnate- -rial. This'iamine is a :secondary amine, having a boilingpoint of 49.3 1F. .and :a melting :point of .32" :It is :readily soluble.in :mineral zacids andlight hydrocarbons. In preparing-10hr amine saltsfrom this :amine, Wvemay use the (1.2.

amine; and this w'as usually done when a pure amine-salt was desired.However, :i-tis not necessary-to use a C.JP.1 .amine. Indeed,incommercial practice, we usually employ the commercial grades-ofuthisamine, which .are readily available as substantiallypure materials.

Thegdi-cyclohexyl amine readilygreacts with the 3-methyl-butyl,;2-.ethyl-;hex;vl brtho ,phos- ,phoricacid; the reactiony-beingtquiteexothermic,

f frequently done inincorporating them in waxes,

asshown in :our .prior application Serial- No. 504,056. .As therestated, in ,makingjour rust inhibitors from these reagents, the reactiontem- ,perature is carefully controlled. Usually, the reactiontemperature is held between .and 200 F.; the reaction mixture beingexternally controlled, .if necessary. I

The other reactant, the acid phosphateesters are di-esters of orthophosphoric acid ,and .may

be represented by the .following generic formula: 50

wherein 'R.,"'R" and R represent hydrogen :or an alkyl grou at least onebranched chain .a'lkyl group'bein present.

ffThese'j acid "phosphate esters can be prepared by'variousmethodsfromalkylated phenols consoluble in mineral oils.

the present purposes.

temperature of the taining one or more branched chain alkyl groupsattached to the phenyl, nucleus in the positions indicated ante.

In particular, the acid phosphate di-esters of 4- tertiary-butyl phenyl,2-tertiary-butyl-4secondary butyl phenol, ZA-di-tertiary-butyl phenol, l

phenyl) phosphate and di-(2,4-di-tertiary-butyl-' phenyl) phosphate areadvantageous in preparing our rust inhibitors.

These two acid phosphate di-esters are viscous oily liquids at roomtemperature and are readily Accordingly, mineral oil solutions of theseacid phosphate esters may be employed in preparing concentrates of ourrust amine being added to such (ll-esters of alkylated phenolscontaining tertiary or secondary alkyl groups are useful andadvanotageous in preparing our rust inhibitors; those containing aplurality of such branched chain alkyl groups being particularlyadvantageous for Such acid phosphate diesters are readily soluble inmineral oils and have other properties rendering them advanfor thepurposes of this invention.

acid phosphate di-esters of tageous As a class, these alkylated phenolscontaining branched chain alkyl groups react readily with di-cyclohexylamine. In general, the reaction is exothermic and is quite vigorous inmost cases. In preparing our rust inhibitors, the reaction temperatureis controlled by suitable means to secure smooth reaction and obtainaddition products of the amine and acid phosphate ester. In doing so,the temperature of the reaction mixture is controlled by cooling orheating as required; the

tained below 180 F. to avoid splitting out water -from the mixture- Thereaction temperature is "usually maintained between 140 and 170 F.during the larger portion of the reaction and within this rangeexcellent rust inhibitors are obtained; the pH value of the reactionproduct being adjusted in the final stages of the reaction within thedesired range stated ante.

The following examples illustrate advantageous methods of preparingthese rust inhibitors:

Example I .-To a suitable kettle equipped with heating and cooling coilsand means for mechanical agitation, there were added 181 pounds ofcommercial di-cyclohexyl amine and then 536 pounds of di(2,4,6-tri-tertiary-.butyl-phenyl) reaction mixture being main-.

4 ciently soluble in mineral oils for the present purposes.

Similar viscous oily rust inhibitors can be readily obtained havingother pH values within the range of 5.5 to 7.5, by controlled adjustmentof the pH during the last stage of the reaction. Likewise, our oily rustinhibitors also can be prepared from other acid phosphate di-esters ofalkylated phenols as well as from the particular acid phosphate employedin Example I. The preparation of other such advantageous rust inhibitorsis illustrated in the following example.

Example II.--Here again, the reaction is carried out in a suitablekettle equipped with means for heating and. cooling and for agitatingthe mixture.

Into such a kettle there. were introduced 181 pounds of commercialdi-cyclohexyl amine and then 47 pounds ofdi-(2,4-di-tertiary-butylphenyl) phosphate were gradually added withstirring. The. reaction was vigorous and quite exothermic and the acidphosphate was' added phosphate were slowly added, the said acid phos-'phate being gradually added at such rate as to keep the temperature ofthe reaction mixture below 180 F. whereby to avoid splitting out waterfrom the mixture. After the addition of the acid phosphate, the mixturehad a pH of 4.1 and was brought to the desired pI-I of 7.3 by adding14.0 pounds of di-cyclohexyl amine and stirring the final mixture forone hour.

The substantially neutral reaction product so obtained is a .heavyviscous oily liquid when cooled to room temperature. This reactionproduct or rust inhibitor was light amber red in color and had apleasant odor. It' was sufliat such a gradual rate asto facilitatemaintaining the reaction temperature below 180 F., the

reaction mixture being cooled if desired to maintain it below thattemperature. In thisway, the

reaction temperature was maintained between 140 and 170 F. during thelarger portion of the reaction. After all the acid phosphate had beenadded, the mixture was warmed to facilitate completion of the reaction.At this stage the reaction mixture had a pH between 3 and .4 and thefinal adjustment and control of the pH value was then effected. In doingso, 16.0 pounds of d i-cyclohexylamine were added and the mixturefurther heated with stirring until the reaction product had a pH ofapproximately 6.8.

The rust inhibitor so obtained was a heavy viscous oily liquid whencooled to room temperature and was sufiiciently soluble in mineral oilsfor making our improved compositions. In other words, the substantiallyneutral reaction products obtained in Examples I and II, respectively,like the amine andv acid phosphate esters from which they were prepared,are soluble in mineral oil. Accordingly, .we sometimes prepareconcentrated solutions of these rust inhibitors in mineral oils byforming them in situ in the oil. In such processes, the amine is firstdissolved in the mineral oil and then the acid phosphate ester added,the mixture being stirred and maintained at the desired temperatureuntil the reaction is complete, and the mixture has a pH value withinthe specified range. In preparing such oil concentrates of our rustinhibitors sometimes additional amine is added in the later stages toadjust the pH value as desired. The concentrates or oil solutions ofneutral reaction products so obtained are useful addition agents tovarious types of lubricants. The preparation of such concentrates isillustrated in the following example:

Example III .-l pounds of light mineral lubricating oil having aviscosity of seconds SUV at 100 F. were added to an iron vessel equippedwith means for heating and cooling and the reaction mixture rose to 178F. After stirring for one hour, the pH of the mixture was 4.8. In orderto increase this value to. the desired range, 6.0 pounds ofdi-cyclohexyl amine were added to the mixture and stirred and theresultant mixture had a pH of 6.1. adjustment, 7.0 additional pounds ofdi-cyclohexyl amine were added to the mixture which after stirring forone hour and cooling to room temperature had a pH of 7.4.

The oily mixture prepared in this Example III can be regarded as a sortof concentrated solution which can be stored indefinitely andincorporated in lubricating oils as desired to prepare commercialanti-rust oils and improved lubricants.

In general, the rust inhibitors or reaction products prepared asdescribed ante, may be dissolved in various types of mineral oils andimproved anti-rust and non-corrosive oil compositions obtained which arecapable of inhibiting or retarding' ithe rusting of various metals asdescribed.

What we claim is: 1. As new compositions of matter, useful as rustpreventive compounds and for other purposes, the oil-soluble additionsalts having the following formula:

Y 0 again a.

in! I III To secure a final I substantially neutral compounds soluble inmineral oils and miscible with hydrocarbons.

6. As an improvement in the manufacture of oil-soluble, rust preventivecompounds from acid phosphate di-esters of alkyl-phenols having thefollowing formula:

wherein R, R" and R' representa s'ubstituent equimolecular proportions,while maintaining the wherein R represents a cyclohexyl group and R, a

R" and R' represent a substituent selected from the class consisting ofhydrogen and an alkyl group, at least one branched chain alkyl roupbeing present, said amine salt being a sub-' substantially neutralcompounds soluble in mineral oils'and' miscible with hydrocarbons. v

5. As new compositions of matter, the oilsoluble addition salts ofdi-cyclohexylamine and acid phosphate di-esters of 2,4-di-alkylatedphenols containing at least one branched chain alkyl group, saiddi-cyclohexyl amine salts'belng reaction temperature below 200 F., toproduce substantially neutral addition products thereof. 7. The processof claim 6 wherein the reaction is effected at temperatures between 140and 200 F.

8. As an improvement in the manufacture of oil-soluble, rust preventivecompounds, the improved process which comprises reacting dicyclohexylamine with acid phosphate di-esters of 2,4,6-tri-alkylated phenolscontaining at least one branched chain alkyl group, at temperaturesbetween 140 and 200 F., the said amine and acid phosphate ester beingreacted and combined in substantially equimolecular proportions to formsubstantially neutral addition products thereof.

9. The process of claim 8 wherein said acid phosphate di-esterisdi-(2,4,6-tri-tertiary-butylphenyl) phosphate.

' 10. The process of claim 8 wherein said acid phosphate di-ester isdi-(2,6-di-tertiary-butyl-4- methyl-phenyl) phosphate.

11. As an improvement in the manufacture of oil-soluble, rust preventivecompounds, the improved process which comprises reacting di-' cyclohexylamine with acid phosphate di-esters of 2,4-di-alkylated phenolscontaining at least one branched chain alkyl group, at temperaturesbetween and 200 E, the said amine and acid phosphate ester being reactedand combined in substantially equimolecular proportions to formsubstantially neutral addition products thereof.

12. The process of claim 12 where said acid phosphate di-esterisdi-(2,4-di tertiary-butylphenyl) phosphate.

HERSCHEL G. SMITH. TROY L. CANTRELL.

